Now for my list... If I had to pick only 3, they would be:
1. Ah! My Goddess (more than just the OAD that is coming out this summer)
2. Spice and Wolf
3. Full Metal Panic! (There have been hints and teases. Please make more!)

However, the following are also shows that I would love to see more of:
Mysterious Girlfriend X
Otome Youkai Zakuro
The Melancholy of Haruhi Suzumiya
Hyouka
Bodacious Space Pirates (beyond the upcoming movie)
Kokoro Connect
My Little Monster
Pet Girl of Sakurasou (assuming they have not completed the entire light novel series yet)
Tari Tari (There is room for at least a movie there)

Highschool of the Dead - We all know that this isn't the end. Please make season 2 happen!
Infinate Stratos - This was only their first year and they already got into this much trouble. Bring on the 2nd season.
Dog Days - Season 1 had alot of action and season 2 added more characters. What's next?
Sekirei - Same as HOTD, we know it's not the end. In the end I had more questions than answers. Come on Season 3.

Highschool of the Dead - We all know that this isn't the end. Please make season 2 happen!
Infinate Stratos - This was only their first year and they already got into this much trouble. Bring on the 2nd season.
Dog Days - Season 1 had alot of action and season 2 added more characters. What's next?
Sekirei - Same as HOTD, we know it's not the end. In the end I had more questions than answers. Come on Season 3.